Many examples of devices of this type are known.
Such electrical supply devices are for example used for supplying electrical machines of motor vehicles of the electrical and/or hybrid type, that is to say combining an electrical machine and a conventional thermal engine, for which it is important to be able to recover the kinetic energy in order to recharge the vehicle battery and supply the onboard system with electrical power. This function is normally referred as recuperative braking. A battery of the metal hydride type is for example used.
These electrical supply devices do however pose many problems.
This is because the energy storage units undergo numerous charging and discharging cycles. For example, when the motor vehicle stops, a very intense discharge of electricity occurs. For example again, the storage units are charged with a high-intensity electric current during periods of recuperative braking.
When electric current is released, during discharge operations, or stored during charging operations, the storage units give off heat. The quantity of heat given off is proportional to the intensity of the electric current flowing in charge or discharge mode.
In addition, these charging and discharging cycles are liable to follow each other at a very high rate, in particular when the vehicle is travelling in town and the driver is caused to stop and restart the vehicle frequently.
However, so that the storage units can effectively store the electric current, they must be maintained within a range of operating temperatures that is bounded by a maximum operating temperature and a minimum operating temperature.
When the charging and discharging cycles follow each other rapidly, the temperature of the storage units is liable to rise very quickly beyond the maximum operating temperature. The temperature rise of the storage units is all the greater when the storage units are arranged in a closed box.